Various components of electrical connectors are fabricated of sheet metal material, as in a continuous stamping and forming operation. Terminals or contacts and EMI/RFI shields are examples. As is conventional in stamping and forming operations, the components are carried through the stamping and forming stations by integral carrier means of the sheet metal material, such as a pair of generally spaced carrier strips, with the components being stamped and formed between the strips. The carrier strips or webs are often provided with spaced apertures whereby the webs not only carry the components through the various stamping and forming operations but the webs are used for indexing purposes in the various operational machines.
As is known, once the components are stamped and formed in their final configurations, they can be removed from the carrier strips and plated (e.g., barrel plated) or they can remain attached or integral with the carrier webs and the composite strips are wound onto reels for subsequent processing, such as plating operations, or for subsequent assembly of the components into electrical connector assemblies. In the alternative, the components can be partially formed, plated and then formed to their desired final configuration.
Various problems are encountered in fabrication techniques as described above. One of the problems involves damage to the components during handling and processing after the stamping and forming operations, during or after the composite strips being wound onto reels. For instance, a shield for a conventional input/output (I/O) electrical connector may include a base plate with various portions projecting therefrom. Grounding legs and tabs may be integrally formed and project from the base plate for insertion into grounding holes in a printed circuit board. Locking tabs may project from the base plate for locking the plate to a housing or other component of the electrical connector. The shroud of the shield also projects from the base plate. These portions may and typically do project in different directions.
Each of these projections is susceptible to being damaged, bent or tangled as the separated or individual components are plated in a barrel plating operation. They also are prone to being damaged during winding of the shields (extending between parallel carrier webs) onto reels, during subsequent fabricating processes such as plating when the composite strip is unwound from the reel and again wound back on the reel, and during subsequent assembly operations prior to or during assembly of the shield on the connector housing. Methods of protecting the projecting portions of the shield are therefore a significant issue because minimizing damaged parts reduces scrapped parts.
Protection of relatively fragile components is further an issue because in the past, shields were typically formed with the access of the open-ended shroud portion of the shell oriented perpendicular to the plane of the carrier web. If the shells are plated while on the carrier web, the entire shell and carrier web composite is submerged and moved through the plating bath. Because of the orientation of the shroud relative to the direction of travel of the carrier web composite, non-uniform plating may occur since: 1) the distance between the anode and the outer surface of the shell varies which causes the center of the outer surface to receive the least amount of plating; 2) adjacent shells shield each other from the current; and 3) the plating fluids do not uniformly flow through and around the shroud opening. In addition, such an orientation of a shell that includes integral ground tabs oriented perpendicular to the shroud axis does not readily permit selective plating of the ground tabs only, with a different metal or a different thickness of plating.
Rotation of the shell so that the plane of the flange from which an (i.e., an axis through the shroud opening is parallel to the plane of the carrier web) the open-ended shroud portion extends is perpendicular the plane of the carrier web permits the plating fluids to more evenly flow through the shroud which results in more uniform plating. The ground tabs then project beneath the carrier web and the shroud portion of the shell which readily permits selective plating of only the ground tab as referred to above. However, since the tabs project perpendicularly relative to the direction of movement of the carrier web, they are prone to becoming damaged during reeling and handling operations. Protection of these tabs is thus desirable.
If the components are partially formed and then plated, the plating may crack during subsequent forming operations. This is especially important for the manufacture of shields for connectors because the shield connects the electrical connector to a ground circuit. Because the plating such as nickel applied to a steel shield is a better conductor than the steel shield itself, cracks in the plating interrupt the ground path which decreases the shielding effectiveness of the shield and thus its EMI/RFI performance. Another problem is possible corrosion of the base metal of the shield due to exposure caused by cracks in the plating.
A further problem in stamping and forming such components involves the undue longitudinal spacing between the components, lengthwise relative to the carrier webs. That is, taking the I/O shield again as an example, considerable sheet metal material is required to produce the shield into its ultimate configuration. Once formed, relatively large spacings or gaps result between the centers of adjacent shields lengthwise relative to the carrier webs. This results in the wound composite reels being of undue size or diameter or permits a relatively few number of parts per reel.
It is known that U-shaped corrugations can be formed in the portion of the carrier webs between adjacent metal components in order to reduce the spacing between such metal components and thus permit a greater number of components on a reel of a given diameter. Such corrugations are typically formed in a multi-station forming operation which results in additional complexity for the forming die. The forming operation utilized to create the U-shape involves a manufacturing trade-off in that the fewer stations utilized to form the U-shape, the greater the likelihood that the metal will stretch and become thinner during the forming process. In addition, such stretching is likely to not be uniform which would result in inconsistent spacing between components from production run to production run due to slight changes in the material thickness and mechanical properties. This makes subsequent automated handling and assembly more difficult.
Another problem with the U-shape is that during a process such as plating, the shells and their connecting carrier webs or strips are unreeled and run through a plating bath and then re-reeled. The distance between the supply reel and the take-up reel is typically between 40 and 120 feet. Due to the weight of the shells and the carrier webs, the flexibility of the metal carrier strip and the unsupported length between the reels, the U-shaped portions utilized to reduce the spacing between the shells will deform or stretch so that the two legs of the U-shaped member are no longer generally parallel. This will increase the spacing between adjacent shells and thus reduce the effectiveness of the space reduction. In addition, because the U-shaped portions will not stretch uniformly, the spacing between adjacent shells will be somewhat inconsistent which makes subsequent automated handling of the shells and assembly of the connector more difficult.
This invention is directed to solving the above problems and satisfying the stated needs.